python练习(一)

1. 实现1-100的所有的和

def qiuhe(x, y):
return x + y

he = 0
for i in xrange(1, 101):
he =qiuhe(he,i)
print (he)

2. 实现1-500所有奇数的和

def is_odd(x):
    return x % 2 == 1
def qiuhe(x, y):
    return x + y

he = 0
for i in filter(is_odd,xrange(1,501)):
    print (i)
    he = qiuhe(he, i)
print (he)

3.求1+ 2! + 3! + 4! + ……20！的和

def qiuhe(x, y):
    return x + y

def jiecheng(n):
    if(n<=1):
        return 1
    else:
        return jiecheng(n-1)*n

he = 0
for i in xrange(1, 21):
    he +=jiecheng(i)
print (he)

4.对指定一个list进行排序[2,32,43,453,54,6,576,5,7,6,8,78,7,89]

list.sort() 在本地进行排序，不返回副本
或者

def cmp_value(x,y):
    if x > y :
        return 1
    elif x < y:
        return -1
    else:
        return 0

listsorted=[2,32,43,453,54,6,576,5,7,6,8,78,7,89]
so=sorted(listsorted,cmp=cmp_value)
print (so)

5.字典排序，字符串， list， tuple常用方法

字典排序:

import operator
d = {'data1':3, 'data2':1, 'data3':2, 'data4':4}
print (sorted(d.iteritems(),key=operator.itemgetter(1)))

list:

classmates = ['Michael', 'Bob', 'Tracy']
#len
print (len(classmates))

#index
print (classmates[0])

#-1
print (classmates[-1])

#append
classmates.append('Adam')
print (classmates)

#insert
classmates.insert(1,'Jack')
print (classmates)

#pop
classmates.pop(1)
print (classmates)